This invention relates to vehicle air conditioning systems; and more particularly relates to a novel and improved air conditioning system which employs a pair of compressors interconnected between condenser and evaporator sections in a unique and highly efficient manner.
Railway car air conditioning units customarily employ a high voltage power source that is capable of providing enough electrical power to run a pair of roof-mounted compressors between a pair of condensers and pair of evaporators. In such systems, however, the compressors are independently connected between one of the condensers and evaporators so as to in effect define a pair of single loop systems. In that way, if one of the single loop systems becomes inoperable, the other one would continue to deliver conditioned air to the interior of the railway car from the one evaporator section still in use.
The problems in air conditioning systems for vehicles other than trains or railway cars are somewhat different in that, for example, in a bus air conditioning system the generator does not have the same capacity as the power source used on railway cars and is not capable of providing as much electrical power; also, under peak load conditions, there may be insufficient power from the generator to keep the air conditioning system in operation. For this reason, in the past, no one has successfully devised a way of utilizing a dual loop system on a bus or other vehicle in which a generator is employed as the power source to continue to run the system under peak load conditions. Accordingly, in such systems which utilize a generator as a power source, it is desirable to employ a pair of compressors which individually require less power to maintain the air conditioning system in operation than the single compressor. As a result, if there is insufficient power generated to run both compressors, it is possible to use a single compressor at what amounts to a half or partial load and continue to supply conditioned air to the interior of the bus. Still further, it is highly desirable that the system for a bus be set up as a dual loop system so that the refrigerant lines from each compressor and condenser run through each of the evaporator coils and the compressors can be successively during the warm-up or initial start-up period to minimize the load on the compressors.
It is therefore an object of the present invention to provide for a novel and improved air conditioning system for automotive vehicles, such as, busses.
It is another object of the present invention to provide for a novel and improved roof or rear-mounted air conditioning system for automotive vehicles employing a unique form of refrigerant supply system between condensor and evaporator sections and which is specifically adaptable for use with a pair of compressor units.
A further object of the present invention is to provide in an air conditioning system for a novel and improved form of refrigerant supply arrangement between condenser and evaporator sections which enables operation at less than full capacity; and further wherein the system incorporates a pair of compressors so that, if one compressor should be out of action, the remaining compressor will continue to supply conditioned air through the same outlets as when the system was fully operational.
A still further object of the present invention is to provide a roof-mounted air conditioning system for busses or other automotive vehicles including a pair of roof-mounted compressors interposed between a pair of condensers and evaporators and wherein each compressor is characterized by supplying refrigerant to each of the evaporator sections independently of one another.
In accordance with the present invention, there has been devised an air conditioning system adapted for mounting on a vehicle in which a pair of condenser sections each includes a condenser coil, first means for circulating air across each of the condenser coils, a pair of evaporator sections, a and air circulating ducts for directing conditioned air into the vehicle, the improvement comprising a pair of compressors, each of the compressors including a first refrigerant line for delivering refrigerant to one of the condenser coils and a second refrigerant line for delivering refrigerant from the evaporator coils in each of the evaporator sections to one of the compressors, each of the evaporator sections including a plurality of evaporator coils, the evaporator coils in each evaporator section being substantially coextensive with one another and with said ducts, and a third refrigerant delivery line extending from each of the condenser coils to one of the evaporator coils in each of the evaporator sections.
In a preferred form thereof, each of the compressors includes a separate motor drive whereby each of the compressors is operative to deliver refrigerant from one of the condenser coils, in the event that one of the compressors is disabled, to at least one of the evaporator coils in each of the evaporator sections. The refrigerant delivered from each compressor to each of the condensor coils is a high pressure vapor and from each of the evaporator coils to each of the compressors is a low pressure vapor while the refrigerant delivered from each of the condenser coils to the respective evaporator coils is a high pressure liquid.
Most desirably, the condenser and evaporator sections are modular roof-mounted sections, and the compressors either may be rear-mounted directly adjacent to the generator or roof-mounted between the condensor and evaporator sections. In either mounting, each compressor is capable of supplying refrigerant to each of the evaporator sections independently of the other compressor in the event that one of the compressors should become incapacitated.
There has been outlined the more salient features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.